As this type of rail attachment apparatus for an electrical device, for example, rail attachment apparatuses described in Patent Literatures 1 and 2 have been suggested.
A conventional example described in Patent Literature 1 comprises a slider which includes a coil spring disposed on a rear side of a frame of an electromagnetic contactor and is biased toward a rail side, and a support column having a hook portion at its tip is disposed adjacent to a rail on an inner bottom surface of a case, this hook portion being engaged in a hook hole of the slider.
A conventional example described in Patent Literature 2 comprises a first engaging portion and a second engaging portion opposed to engage with both side edges of a rail, and a wire spring which presses the side edge of the rail engaged with the first engaging portion, a spring biasing force of this wire spring being given to the rail so that the other rail edge is pressed by the second engaging portion.